A compact light weight robot built to pull weight

Step 1: Materials

4 x chassie rails
1 x medium large wheel
2 x large wheel
2 x small chassie rails
2 x motors
1 x vex net
13 x collars
6 x flat bearings
2 x 36 teeth gears
2 x 84 teeth gears
8 x 3/4 screws
3 x 3/8 screws
1 x large rail bar
18 x spacer
2 x small bars
2 x medium bars
1 x large bar
1 x 9 hole bar
18 x keps nut
4 x hollow bars
SLED
5 x bearing blocks
1 x 9 hole bar
2 x large hollow bars
12 x keps nut
TOOLS
large hex wrench
small hex wrench
regular wrench

Step 2: Building the Frame

so with the original robot build, you wont need to remove much but the vetnet box that will be moved up eventually.
the frame should look the same except for the front bar which should be replaced with 2 small 4 hole rails. This is so you can put a medium/large wheel up front.

Step 3: Front Wheel

As you can see in the photos, we put 2 rails with 4 holes in the front where the old large rail was sitting and with that open space in the middle we were able to put the medium wheel in the front to increase the torque alot.

Step 4: Gear Ratio

our gear ratio is 84:36 or 7:3, we chose this gear ratio because it gives alot of speed but our big wheels give it some torque, Input RPM - 238.8 VS Output RPM - 171.936, Input Torque - 1.67 VS Output Torque - 2.3194

Step 5: Wheel Size

we used these wheels because they offer alot of torque and a bit of speed. The theoretical speed is 1.6 cm/seconds. The actual speed is 1.72 cm/second.

Step 6: Motor Placement

we use the 4 hollow bars to hold the vexnet box up top, with the box up top we can put the big wheel in the front and we were able to experiment with larger gears because we had tons of space.

Step 7: Sled

we have a 5:15 bar with 5 bearing blocks on the bottom that makes it move better. this sled is used for weights so we can see how strong our robot is. the two hollow bars on the top are used for holding the weights in place. we uswe the complex angle bars and small angle bars to drop the sled down to ground level because we have huge wheels.